1. Field of the Invention
The present invention relates to image encoding and decoding, and more particularly, to an image encoding apparatus, method, and medium and an image decoding apparatus, method, and medium for encoding and decoding an original image to achieve a required compression rate while reducing the complexity of a decoding unit, and a display driving circuit and method and medium using the same.
2. Description of the Related Art
Multimedia devices such as mobile phones, personal digital assistants (PDAs), digital cameras, and notebook computers generally use a liquid crystal display (LCD) panel or an organic electro luminescence (EL) as a display unit. The display unit receives image data from a display driving circuit including a memory and displays an image. At this time, image data to be displayed is sequentially input to and stored in the memory.
As the size of image data that can be displayed by a display unit increases and images displayed on a multimedia device come to have high resolution and multiple gradations, the size of a memory that stores the image data also tends to increase. With this tendency, the size of a display driving circuit also increases, causing the manufacturing cost of the display driving circuit to increase. To reduce the size of the memory, the image data is compressed to be stored in the memory and is decompressed to be displayed.
When a multimedia device has a quarter video graphic array (QVGA) resolution, i.e., a resolution of 320×240 or 240×320, a display driving circuit using compression technology processes one pixel per clock during encoding. However, during decoding, since a clock is not separately assigned, the display driving circuit should process pixels corresponding to a line per clock, i.e., 240 or 320 pixels, at a time. As a result, the complexity of a decoding unit increases and the hardware size and driving power of the display driving circuit also increase.
U.S. Pat. No. 6,774,892 and US Published Patent Application No. 20040051717 disclose display driving circuits.